This invention relates to a method of manufacturing a bag from thermoplastic material and is particularly directed to a method of manufacturing a "square bottom bag," i.e. a rectangular, flat bottom bag from a sheet of heat-sealable plastics material such as polyethylene, polypropylene, and the like.
Carry-out bags commonly used in grocery and supermarket stores conventionally have been manufactured from paper of heavy weight and often of double plie structure to provide adequate strength to the bag and to permit the bag to stand upright. Paper bags, however, suffer from the disadvantage of tearing when improperly loaded, overloaded or wetted by groceries.
Bags formed of plastics film are well known as a substitute for paper bags and are available in a variety of designs. For example, it is well known to provide flat bottoms on bags formed from tubular stock. However, known methods of manufacture normally require a multiplicity of method steps which necessitate complex machinery with attendant high capital and operating costs.